Time course of AQP4 expression during edema formation and resolution. (A) Histological evaluation depicted an initial upregulation of AQP4 as early as 1 dpi (§, p = 0.003, Wilcoxon test) that plateaued at 1 and 3 dpi. A significant increase in AQP4 expression was found during the MRI-defined edema resolution compared to the MRI-defined edema formation phase (*, p < 0.0001 Mann Whitney). RNA quantification (B) and protein quantification with western-blot (C) confirmed a much stronger increase in the expression of AQP4 during the MRI-defined edema resolution compared to the MRI-defined edema formation phase (*, p < 0.05 Mann Whitney).The inset in (B) shows the area of the tissue micro-dissection. A tissue block of 3 mm was cut around the injection site. Within the block, samples from the injured and contralateral sides were obtained using a 3-mm-core unipunch (right and left shaded circles). In (C), a representative western blot shows the strong increase of AQP4 at 14 and 20 dpi, while actin, which was used to control loading variations, was stable.